A VA-mode liquid crystal display device has the advantages of a large viewing angle, a high contrast, free of friction alignment, and so on, such that VA mode becomes a common display mode for liquid crystal display devices used in large-size TVs. The VA-mode liquid crystal display device generally uses a multi-domain structure to reduce color shift, so that reliable and stable alignment of liquid crystal molecules is the basis for the VA-mode liquid crystal display device to accurately display a picture. At present, alignment of liquid crystal molecules is achieved substantially by cooperation between an electric field and a specially designed pixel electrode.
FIG. 1 schematically shows the structure of a pixel electrode of a VA-mode liquid crystal display device which is generally used in the prior art. As shown in the figure, the pixel electrode includes a cross-shaped trunk electrode and a plurality of branch electrodes intersecting with the trunk electrode at specific angles. The trunk electrode is located at a middle position of the pixel electrode, mainly for connecting the branch electrodes, and the trunk electrode generally has a larger width than the branch electrode, so as to ensure stability of the structure. When a specific gray-scale voltage is applied to the pixel electrode, the liquid crystal molecules, under a combined action of the electric field and the pixel electrode, are deflected from a periphery toward a center of the pixel electrode along directions of the branch electrodes. As the directions of the branch electrodes on the pixel electrode are different, different display domains can be formed.
However, a liquid crystal display device having a pixel electrode with the above-described structure may produce dark areas when an image is displayed. This is because a deflection angle of the liquid crystal molecules located at the trunk electrode is the same as a deflection angle of upper and lower polarizers. Such being the case, transmittance at the trunk electrode is zero, and the dark areas thus occur around the trunk electrode. This affects a display effect of the liquid crystal display device. In particular, when a curved surface is used, dislocation of upper and lower substrates while being bended may widen the dark areas and decrease the transmittance of a pixel unit. This leads to generation of dark areas on a liquid crystal display screen and to deterioration in quality of an image.
To conclude the above, it is in urgent need to improve the structure of the pixel electrode, so as to reduce occurrence of the dark areas.